Messages in this thread | | | From | Dmitry Vyukov <> | Date | Fri, 27 May 2022 15:52:12 +0200 | Subject | Re: [RFC PATCH v3] UML: add support for KASAN under x86_64 |
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On Fri, 27 May 2022 at 15:27, Johannes Berg <johannes@sipsolutions.net> wrote: > > On Fri, 2022-05-27 at 15:18 +0200, Dmitry Vyukov wrote: > > On Fri, 27 May 2022 at 15:15, Johannes Berg <johannes@sipsolutions.net> wrote: > > > > > > On Fri, 2022-05-27 at 15:09 +0200, Dmitry Vyukov wrote: > > > > > I did note (this is more for kasan-dev@) that the "freed by" is fairly > > > > > much useless when using kfree_rcu(), it might be worthwhile to annotate > > > > > that somehow, so the stack trace is recorded by kfree_rcu() already, > > > > > rather than just showing the RCU callback used for that. > > > > > > > > KASAN is doing it for several years now, see e.g.: > > > > https://groups.google.com/g/syzkaller-bugs/c/eTW9zom4O2o/m/_v7cOo2RFwAJ > > > > > > > > > > Hm. It didn't for me: > > > > Please post a full report with line numbers and kernel version. > > That was basically it, apart from a few lines snipped from the stack > traces. Kernel version was admittedly a little older - 5.18.0-rc1 + a > few UML fixes + this KASAN patch (+ the fixes I pointed out earlier) > > I guess it doesn't really matter that much, just had to dig a bit to > understand why it was freed.
Humm... I don't have any explanation based only on this info. Generally call_rcu stacks are memorized and I see the call is still there: https://elixir.bootlin.com/linux/v5.18/source/kernel/rcu/tree.c#L3595 It may be caused by some narrow races, depleted reserve memory in stackdepot, or race with quarantine eviction.
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